2003 Progress Report: Bioturbation and Bioavailability of Residual, Desorption-Resistant Contaminants

EPA Grant Number: R828773C001
Subproject: this is subproject number 001 , established and managed by the Center Director under grant R828773
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).

Center: HSRC (2001) - South and Southwest HSRC
Center Director: Reible, Danny D.
Title: Bioturbation and Bioavailability of Residual, Desorption-Resistant Contaminants
Investigators: Reible, Danny D. , Fleeger, J. W. , Pardue, J. , Tomson, Mason B.
Current Investigators: Reible, Danny D. , Fleeger, J. W. , Pardue, J.
Institution: Louisiana State University - Baton Rouge , Rice University
EPA Project Officer: Lasat, Mitch
Project Period: October 1, 2001 through September 30, 2006 (Extended to September 30, 2007)
Project Period Covered by this Report: October 1, 2002 through September 30, 2003
Project Amount: Refer to main center abstract for funding details.
RFA: Hazardous Substance Research Centers - HSRC (2001) RFA Text |  Recipients Lists
Research Category: Hazardous Waste/Remediation , Land and Waste Management

Objective:

The objective of this research project is to evaluate the bioavailability of the desorption-resistant fraction of contaminants using uptake and accumulation in tubificid oligochaetes. Work to date has confirmed that the route of uptake (i.e., sediment ingestion or porewater absorption) and organism-specific factors (e.g., assimilation efficiency and elimination kinetics) control the kinetics of accumulation of the desorption-resistant fraction of polycyclic aromatic hydrocarbons (PAHs). However, the ultimate, or steady state, accumulation is controlled by porewater partitioning as defined by physicochemical measurements. This research project seeks to test the applicability of this paradigm to field-contaminated and aged sediments that exhibit extremely slow-release kinetics in physicochemical measurements. The effect of kinetics of release on uptake kinetics and extent also will be explored with a mathematical model of chemical desorption resistance. In addition, the implications of this paradigm for other hydrophobic contaminants, such as polychlorinated biphenyls (PCBs), that are believed to biomagnify will be evaluated.

Progress Summary:

Sediment quality is determined by the risks of contaminants to human and ecological receptors, which, in turn, is controlled by availability and exposure to those contaminants. A significant fraction of the organic contaminants in soils and sediments may not be readily available for uptake and organism effects. A desorption-resistant fraction often is observed that is released more slowly and in lesser amounts from contaminated sediments. The slowed rates of physicochemical release have been reflected in microbial degradation processes. Until recently, however, there has been limited assessment of the bioavailability of this fraction beyond microbial assays. Multicellular animals, notably deposit-feeding benthic organisms, represent a more intense environment for the assessment of bioavailability and are more directly linked to the food chain. Results with a limited set of laboratory-inoculated sediments and PAH contaminants suggest that the ultimate organism uptake of desorption-resistant contaminants is reduced compared to reversibly desorbed contaminants, but is predictable with a biphasic equilibrium model. The preliminary work also suggests that the rate of uptake by benthic organisms is enhanced relative to that expected by physicochemical desorption measurements. This research project is primarily aimed at confirming the preliminary results and extending the database of compounds and sediments for which bioavailability is understood. The ultimate objective is to develop a predictive model of biological availability based on physicochemical availability.

Approach

Methodology. In previous reports, many of the basic techniques employed in the project were discussed and will not be repeated here. The fundamental approach has been to prepare sediments effectively containing only the desorption-resistant fraction of contaminants and monitor the accumulation of the contaminants in deposit-feeding tubificid oligochaetes such as Ilyodrilus templetoni. Deposit-feeding oligochaetes represent an intense processing environment for the sediments, and thus, bioavailability tests employing these organisms are not complicated by the mass-transfer resistances that are inherently associated with microbial assays of bioavailability. Readily desorbed contaminants are removed from inoculated sediments in these studies by either dilute isopropanol washes or, more recently, mixing with XAD-2. By either approach, essentially complete removal of the reversibly sorbed contaminants can be achieved rapidly and easily, allowing use of the residual sediment to explore the bioavailability of the desorption-resistant fraction. Low-residual concentrations have led to the use of radiolabled contaminants for much of the work to date. Both the kinetics and steady-state uptake into the oligochaetes have been measured. Uptake from sediment ingestion was compared to uptake from water alone to evaluate the influence of route of exposure on rate and extent of accumulation in the organism.

Current work proposes the expanded use of field-contaminated sediments to evaluate the generality of the results to date. Models are under development to assist in relating physicochemical desorption kinetics to observed uptake and accumulation. Finally, methods for evaluating the relationship between bioavailability to benthic organisms and trophic transfer up the food chain are under development. These methods will be discussed in more detail in the discussion of future work.

Outputs/Accomplishments. Efforts over the past year have focused on:

• Increasing the number of contaminants and sediments for extension of the porewater paradigm for the prediction of steady-state uptake in benthic organisms

• Comparing the rate and steady-state uptake by porewater absorption and sediment-ingestion and identifying the dominant route of uptake for particular compounds

• Development of a model of physicochemical sorption and desorption processes to relate the kinetics of desorption to the kinetics and extent of uptake.

Figure 1 presents predicted biota-sediment accumulation factor (BSAF) values for the reversibly sorbed and desorption-resistant fraction of phenanthrene-amended sediments (six sediments total), two desorbed benzo[a]pyrene (BaP)-amended sediments, sequestered phenanthrene in "aged" University Lake sediment; the BSAF values for pyrene inferred from Millward, et al., 2001; and a similar estimate of BSAF values reported by Kosian, et al., 1999. BSAF is the ratio of the accumulation in the organism normalized by lipid content to the sediment concentration normalized by the fraction of organic carbon. The predicted BSAFs assume that the effect of desorption resistance is to reduce porewater concentrations without reducing the ratio of porewater concentrations to lipids. That is, the model assumes that steady-state accumulation in the lipids is given approximately by Klw Cpw, where Klw is the lipid-water partition coefficient (approximately Koc), and Cpw is the porewater concentration. The high correlation (r2 = 0.92) between the predicted and the measured BSAFs strongly supports the paradigm that sediment porewater concentration controls the ultimate accumulation of a specific organic contaminant.

Figure 1. Predicted BSAF Values for Various Sediments

The correlation of uptake with porewater concentrations for compounds over the entire range of hydrophobicity from phenanthrene (Log Koc ~ 4.3) to BaP (Log Koc ~ 6) is initially surprising in that phenanthrene is expected to be taken up into organisms by absorption from porewater, whereas sediment ingestion should be more important for more hydrophobic compounds. To test this hypothesis, the route of uptake was evaluated by comparing the kinetics of uptake of both phenanthrene and BaP in separate porewater and sediment exposure experiments. Porewater uptake was measured directly, but that resulting from sediment alone was estimated via development of a toxicokinetics model with separate measurements of assimilation efficiency, elimination rate, ingestion rate, and comparison. The results are shown in Figure 2.

Note also that phenanthrene uptake was essentially complete within 24 hours, but BaP required more than 600 hours to achieve steady state. Thus, the kinetics of uptake was controlled by route of uptake, but the equilibrium uptake was still well estimated by the porewater concentration. Note also that the measured single-gut passage assimilation efficiency of BaP by the organisms was nearly 80 percent, far higher than the fraction of BaP that would be expected to be released from the sediments by physicochemical processes alone during the ½ to 2 hour gut exposure. Thus, I. templetoni appears able to effectively desorb tightly bound contaminants from the sediments after ingestion, and yet steady-state uptake is well described by porewater concentrations. This agreement with physicochemical predictions at steady-state accumulations may be a function of elimination/biodegradation of PAH, which allows the organism to achieve an equilibrium with the surrounding porewater/sediment complex. The extent of solubilization of contaminants in digestive fluid has been proposed as a measurement of bioavailability (Mayer, et al., 1996; Weston and Mayer, 1998). Our data would suggest, however, that such measures would indicate only the rate of uptake of ingested contaminants and not the steady state, or ultimate, bioavailability. This potentially controversial result, however, may be limited to the PAHs and organisms considered herein. Many organisms sorb and even metabolize PAHs relatively effectively (compared to more refractory compounds and potential biomagnifiers such as PCBs). On the basis of the currently available data, it also is not possible to exclude the possibility that this result is an artifact of working with laboratory-inoculated sediments that exhibit less desorption resistance and faster physicochemical equilibration times.

Figure 2. The Top Two Figures Show That Phenanthrene Uptake is Consistent With Uptake From Water, While the Bottom Two Figures Show That BaP Uptake is Almost Entirely Predicted To Occur From Sediment Ingestion

An effort to develop a mathematical model of sorption and desorption in the various organic carbon phases of the sediment was initiated to better understand the factors leading to desorption resistance and the relationship between physicochemical desorption (both rate and extent) and uptake in the deposit feeders. There are a variety of models and interpretations of desorption-resistant phenomena; however, the following ideas are well accepted:

• Approximately biphasic desorption phenomena results from organic carbon heterogeneity. Sediment/soil organic matter can be classified into two general categories: amorphous or condensed-phase organic matter. Denotations such as "coal-derived" particles, "soot carbon," "black carbon," and "hard carbon" have been used to represent condensed-phase organic carbon, which exhibits elevated adsorption capacity and a higher carbon normalized partition coefficient.

• The desorption resistance of organic contaminants and aging effects (i.e., reduced contaminant release over simple reversible sorption behavior) results from the slow diffusion of contaminants from the condensed-phase organic carbon and the increased equilibrium partition coefficient of this material.

The model currently undergoing development and testing has the following features that are consistent with these basic ideas:

• Contaminant sorption and desorption into natural organic matter is assumed to be reversible and at rates that are controlled by diffusion in the pore space of this phase. There exist measurements in the literature of basic physical characteristics of this phase necessary to predict the rates and extent of sorption to this phase.

• Contaminant sorption and desorption to condensed-phase organic matter is assumed to be controlled by diffusion in a solid organic phase. Various equilibrium characteristics of this phase are known or can be measured, but only broad guidance is available for the effective solid-phase diffusion coefficient and the surface area to volume ratio of this phase (the single geometric parameter in the formulation of the model). In principle, these quantities could be measured directly if this organic phase could be isolated by either physical means or highly selective measurement techniques, but efforts have been unsuccessful thus far, and it is envisioned that these parameters will be fit to experimental data on a given sediment.

Thus, the model, as it currently is formulated, has effectively two adjustable parameters that can be calibrated to a particular sediment. The assumption is that the model can be calibrated to kinetic information on sorption and/or desorption for a particular compound and sediment, and can be used to predict sorption and desorption characteristics for other time periods or for other contaminants, at least within the same compound class. The testing of this hypothesis currently is being initiated and forms a significant component of the proposed work on this project. Figure 3 shows some preliminary results with a single compound and sediment at different times of sorption and desorption. The model results appear promising, and they suggest that it may be possible to use the model to predict porewater concentrations as a function of time of sorption or desorption and predict accumulation in deposit-feeding organisms that follow the porewater paradigm previously demonstrated.

Figure 3. Ability of the Biphasic Model To Reproduce Phenanthrene Partitioning in Freshly Inoculated Sediments and Sediments Aged 1,000 Days With 10 and 60 Days of Desorption Time

Recommendations and Rationale for Subsequent Work

The key conclusions from the work described above can be summarized as follows:

• Measurements of availability of PAH contaminants to deposit-feeding oligochaetes continue to support the model that partitioning from porewater defines the steady-state accumulation in the organism, even from the desorption-resistant fraction of contaminants.

• Toxicokinetic modeling and experiments suggest that route of exposure and route-specific parameters such as organism assimilation efficiency and elimination rate for sediment ingestion control the kinetics of uptake, but not the steady-state uptake.

• Porewater concentrations (and by inference the bioavailability) appear to be predictable via a biophasic diffusion model with two key parameters associated with the fraction of the organic matter responsible for desorption-resistant phenomena, the effective length scale of the organic matter (volume to area ratio), and the solid-phase diffusivity.

These conclusions, although well supported by the data collected to date, are limited to a relatively small set of contaminants: sediments and organisms. The research project seeks to test the generality of the results by examining a broader range of sediments, including field-contaminated sediments, and extend to other hydrophobic organic compounds for which there is some evidence that they may not behave as simple partitioning contaminants.

Work with field-contaminated sediments has been limited thus far because of the difficulties of separating sufficient quantities of dissolved contaminant for analysis from the sediment and suspended colloidal phases. We have been working to overcome these problems and believe that we can now analyze both porewater concentrations and accumulation in lipids of contaminants from the field-contaminated sediments with which we are working. The very limited rate and extent of desorption from field contaminated sediments may provide a significant contrast with the laboratory-inoculated sediments that have been the focus thus far. The modeling efforts initiated above also may allow us to correlate observed desorption behavior and better understand the relationship between desorption time and organism uptake with field-contaminated sediments.

Working with field-contaminated sediments also opens opportunities to work with additional contaminants that may not behave as the PAHs employed in the work thus far. Some PCB congeners often increase in tissue concentrations with increasing food chain length in aquatic systems and thus biomagnify (Morrison, et al., 1996). On the other hand, the biomagnification potential of PAH is generally considered to be low, consistent with our observation that steady-state PAH accumulation is governed by thermodynamic equilibrium between porewater and lipids. Do PCBs behave fundamentally differently? PCBs appear to partition more strongly to lipids than sediment organic carbon (BSAFs in benthic invertebrates are typically 3-4 rather than near unity), but this is not evidence for biomagnification. Evidence for biomagnification is often based on increased absolute concentrations during trophic transfer, but increased absolute concentrations also would be expected if lipid content changes at different trophic levels. Gobas, et al., 1999 models biomagnification as a gut-related process in animals with a diet rich in lipids. Fugacity of PCBs increase with passage through the gut, and this increase allows the predator to obtain a body burden that exceeds its prey. Absorption efficiency of lipids is higher than PCBs, which is thought to contribute to the high uptake of PCBs. Based on our work, this process would increase the rate of PCB uptake, but it is unclear if steady-state lipid-normalized accumulation would be changed. A series of experiments comparing accumulation of PCBs and PAHs during trophic transfer would help identify and contrast the potentially different behavior of these compounds. Tubificid oligochaetes that have accumulated PAHs and PCBs could be fed to a larger predator such as a Grass shrimp (Palaemonetes pugio) to evaluate the effects of trophic transfer on accumulation. In principle, both the rate and steady-state accumulation of PAHs and PCBs could be measured and compared.

Accumulation From Field-Contaminated Sediments

This portion of the research project seeks to confirm that porewater concentrations in field-contaminated sediment predict steady-state accumulation of PAHs in the tubificid oligochaete I. templetoni. The methods for exposing the organisms to contaminated sediments and allowing uptake and accumulation are essentially identical to those used previously. Instead of relying on sensitive radiolabled contaminant analysis techniques, however, conventional high-performance liquid chromatography analysis will be employed to evaluate both porewater concentrations and uptake from selected contaminated sediments. An ideal sediment for this research project has been collected from the Anacostia River in Washington, DC. It contains a variety of PAHs with a total PAH concentration of about 30 mg/kg and PCB concentrations in the range of 1 mg/kg. Porewater concentrations are quite small because of the aged and weathered nature of the sediments. Efforts to collect porewater concentration data by centrifugation of the sediment in 1 L batches, followed by extraction of the expressed porewater with a solvent, has proven successful, and porewater concentrations of selected PAHs have been accurately measured. This allows estimation of effective sediment-water partition coefficients, which can be compared to the accumulation of the contaminants in the lipids of the oligochaete. Sediment and lipid concentration measurements do not provide any detection limit difficulties by comparison to the porewater concentrations.

Basic accumulation measurements (both kinetics and steady-state) also will be supplemented by independent measurements of elimination rate, assimilation efficiency, and ingestion rate for sediment exposure and bioconcentration factor from water measurements. These will likely be conducted in subsequent years and are not expected to be complete during the next performance period. This will allow evaluation of sediment versus porewater uptake kinetic estimates that can be compared to the observed overall accumulation kinetics. Finally, the extractable contaminants (as measured by sorption onto XAD-2) can be compared to assimilation efficiency in the gut of the organism to contrast extraction efficiency by physicochemical and biological processes and to identify the significance of any differences to steady-state uptake. As indicated previously, experiments to date have not shown any influence of extraction (assimilation) efficiency on steady-state uptake.

Because Anacostia River sediments also contain PCBs, accumulation of selected PCBs in the organisms also will be monitored. BSAFs for selected PCB congeners present in the highest concentrations will be measured. This will later be compared to normalized accumulation in organisms that are fed the oligochaetes for evaluation of trophic transfer of PCBs.

Modeling Desorption

The modeling efforts will be focused on expanding the database of physicochemical desorption data on a variety of sediments with varying physical and chemical characteristics, and on exploring the model's ability to correlate that data. We also are collecting literature data that is sufficiently complete to allow correlation to the model. Both collected data and literature data will be incorporated into a Web-accessible database for use by other researchers. Sediments that will be used in this research project are summarized in Table 1, shown separated by the fraction of hard carbon and soft carbon as defined operationally by the percentage of carbon that volatizes after treatment at 375°C (Gustafsson, et al., 1997).

Table 1. Sediments for Investigation of Sorption and Desorption Characteristics (* Denotes Field Contaminated)

Sediment
foc%
focsoft%
fochard%
Bayou Manchac
1.8
52
48
University Lake
6.3
87
13
Peat Soil
18.7
91
9
Indiana Harbor*
13.6
55
45
Anacostia River*
4
71
29
Utica River*
2.1
61
39

As indicated previously, the primary model parameters are associated with the hard carbon, the volume to surface area ratio, and the diffusivity. Other parameters can be estimated from the literature or by separate experiments. Even the primary parameters have some literature guidance (e.g., diffusion in glassy polymers may provide at least an order of magnitude estimate of the diffusivity in the hard-carbon solid phase). These parameters will be fit to desorption data from either inoculated sediment or field-contaminated sediments. The desorption data will be collected by monitoring the decrease in concentration on the solid phase as a function of time using XAD-2 to maintain effectively zero porewater concentration.

Trophic Transfer of PAHs and PCBs

Understanding trophic transfer is necessary to fully appreciate the potential impact of these chemicals to human and ecosystem health because predation on the benthic community represents a significant route of exposure to aquatic food webs. Furthermore, values derived from exposure to sediments (e.g., BSAF) are being used to assess contaminant impacts on nonbenthic organisms, including swimming invertebrates and fishes (Maruya, et al., 1997; Burkhard, 2003), primarily to set conservative criteria for environmental impacts. Nonbenthic organisms may have low BSAF values because they do not readily assimilate contaminants or because they do not derive energy from food webs that originate in the sediment. Unfortunately, no laboratory measurements are available to compare to field values of BSAF and trophic transfer factors for a single species to determine the validity of the use of BSAF for nonsediment animals. Trophic transfer factors are similar to BSAF in that they are normalized for lipid content and represent the ratio of lipid normalized PCB or PAH concentration in a predator to its prey.

Trophic transfer of PAH and PCB from tubificid oligochaetes to an invertebrate predator will be studied. Some PCB congeners increase in tissue concentrations with increasing food chain length in aquatic systems and thus biomagnify (Morrison, et al., 1996). On the other hand, the biomagnification potential of PAH is generally considered to be low. Tubificid oligochaetes are often found in contaminated sediments in very high densities. They also are common prey for many different fishes and invertebrates (Bouguenec and Giani, 1989). Grass shrimp (P. pugio) are common invertebrates found in salt marshes, and they are known as predators on small invertebrates such as annelids (Fleeger, et al., 1999). Grass shrimp also are commonly used as field and laboratory test organisms (Rayburn and Fisher, 1997; Smith and Weis, 1997). I. templetoni will be cultured on field-collected sediment from the Anacostia River near Washington, DC, until their tissues reach equilibrium for PCB and PAH. They will be fed to grass shrimp using the methods of Wallace (Wallace and Lopez, 1996; Wallace, et al., 1998). Briefly, worms will be ground up by tissue homogenization and placed in small gelatin capsules. Capsules will be fed to grass shrimp. Previous research suggests that grass shrimp will completely ingest the capsules. We plan to feed each grass shrimp 15 I. templetoni per day (which represents about 12 % of the mass of a grass shrimp) for 30 days. Shrimp will be sacrificed, and after determining body burdens and lipid contents, trophic transfer factors will be calculated for specific PAHs and PCB congeners. Field-generated BSAF values for grass shrimp have been measured, and comparisons to trophic transfer factors will be made to determine if grass shrimp take up toxicants at a high rate. If the rate of bioaccumulation is slow, it will suggest that low values of BSAF in the field are because of slow ingestion or rapid depuration of the chemical; if trophic transfer factors are high, but BSAF is low from the field, it will suggest that grass shrimp does not benefit from bottom sediments and that its food web does not originate in the sediments.

Specifically, we will test two hypotheses concerning bioaccumulation (i.e., biomagnification) across trophic levels in a food web that begins with contaminated sediment. First, we will test the prediction by Gobas, et al., 1999 that a deposit feeder with a diet low in lipid content should have a lower trophic transfer factor (i.e., BSAF) than a predator with a diet rich in lipids feeding on these organisms. To our knowledge, this prediction has not been tested across a food web beginning with a deposit-feeding worm to a predator by following the same compounds. Comparisons in trends between PAHs and PCBs should be revealing and will suggest if current models of biomagnification are generally effective and predictive. Second, we will test if PAHs and PCBs achieve different lipid-normalized tissue concentrations in a predator feeding on a single-prey species with known levels of contamination. PCBs may bioaccumulate differently if they partition more strongly to lipids than to the sediment organic carbon (compared to PAHs) or if PCBs are eliminated at slower rates than PAHs.

References:

Bouguenec V, Giani N. Aquatic oligochaeta as prey for invertebrates and vertebrates: a review (in French). Acta Oecologica-Oecologia Applicata 1989;10:177-196.

Burkhard LP. Factors influencing the design of bioaccumulation factor and biota-sediment accumulation factor field studies. Environmental Toxicology and Chemistry 2003;22:351-360.

Fleeger JW, Carman KR, Webb S, Hilbun N, Pace MC. Consumption of microalgae by the grass shrimp, Palaemonetes pugio. Journal of Crustacean Biology 1999;19:324-336.

Gobas FAPC, Wilcockson JB, Russell RW, Haffner GD. Mechanism of biomagnification in fish under laboratory and field conditions. Environmental Science and Technology 1999;33(1):133-141.

Gustafsson Ö, Haghseta F, Chan C, Macfarlane J, Gschwend PM. Quantification of the dilute sedimentary soot phase: implications for PAH speciation and bioavailability. Environmental Science and Technology 1997;31:203-209.

Kosian PA, West CW, Pasha MS, Cox JS, Mount DR, Huggett RJ, Ankley GT. Use of nonpolar resin for reduction of fluoranthene bioavailability in sediment. Environmental Toxicology and Chemistry 1999;18(2):201-206.

Maruya KA, Risebrough RW, Horne AJ. The bioaccumulation of polynuclear aromatic hydrocarbons by benthic invertebrates in an intertidal marsh. Environmental Toxicology and Chemistry 1997;16:1087-1097.

Mayer LM, Chen Z, Findlay RH, Fang JS, Sampson S, Self RFL, Jumars PA, Quetel C, Donard OFX. Bioavailability of sedimentary contaminants subject to deposit-feeder digestion. Environmental Science and Technology 1996;30(8):2641-2645.

Millward RN, Fleeger JW, Reible DD, et al. Pyrene bioaccumulation, effects of pyrene exposure on particle-size selection, and fecal pyrene content in the oligochaete Limnodrilus hoffmeisteri (Tubificidae, Oligochaeta). Environmental Toxicology and Chemistry 2001;20(6):1359-1366.

Morrison HA, Gobas FAPC, Lazar R, Haffner GD. Development and verification of a bioaccumulation model for organic contaminants in benthic invertebrates. Environmental Science and Technology 1996;30:3377-3384.

Rayburn JR, Fisher WS. Developmental toxicity of three carrier solvents using embryos of the grass shrimp, Palaemonetes pugio. Archive of Environmental Contamination and Toxicology 1997;33:217-221.

Smith GM, Weis JS. Predator-prey relationships in mummichogs (Fundulus heteroclitus [L]): effects of living in a polluted environment. Journal of Experimental Marine Biology and Ecology 1997;209:75-87.

Wallace WG, Lopez GR. Relationship between subcellular cadmium distribution in prey and cadmium trophic transfer to a predator. Estuaries 1996;19:923-930.

Wallace WG, Lopez GR, Levinton JS. Cadmium resistance in an oligochaete and its effect on cadmium trophic transfer to an omnivorous shrimp. Marine Ecology Progress Series 1998;172:225-237.

Weston DP, Mayer LM. In vitro digestive fluid extraction as a measure of the bioavailability of sediment-associated polycyclic aromatic hydrocarbons: sources of variation and implications for partitioning models. Environmental Toxicology and Chemistry 1998;17(5):820-829.

Future Activities:

Based on the needs outlined above, the future activities of this research project are to: (1) confirm the results to date with field PAH-contaminated sediments, including comparing and contrasting accumulation of PCBs from field-contaminated sediment with that observed for PAHs; (2) continue the modeling efforts to better understand the relationship between desorption rates and the rate and steady-state extent of accumulation in organisms; and (3) compare and contrast trophic transfer of PAHs and PCBs from tubificid oligochaetes to grass shrimp.


Journal Articles on this Report : 7 Displayed | Download in RIS Format

Other subproject views: All 36 publications 13 publications in selected types All 9 journal articles
Other center views: All 279 publications 92 publications in selected types All 63 journal articles
Type Citation Sub Project Document Sources
Journal Article Lu X, Reible DD, Fleeger JW, Chai Y. Bioavailability of desorption-resistant phenanthrene to the oligochaete Ilyodrilus templetoni. Environmental Toxicology and Chemistry 2003;22(1):153-160. R828773 (2004)
R828773 (Final)
R828773C001 (2002)
R828773C001 (2003)
R828773C001 (2004)
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  • Journal Article Lu X, Reible DD, Fleeger JW. Relative importance of ingested sediment versus pore water as uptake routes for PAHs to the deposit-feeding oligochaete Ilyodrilus templetoni. Archives of Environmental Contamination and Toxicology 2004;47(2):207-214. R828773 (2004)
    R828773 (Final)
    R828773C001 (2003)
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  • Abstract: Springer-Abstract
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  • Journal Article Lu X, Reible DD, Fleeger JW. Bioavailability and assimilation of sediment-associated benzo[a]pyrene by Ilyodrilus templetoni (oligochaeta). Environmental Toxicology and Chemistry 2004;23(1):57-64. R828773 (2004)
    R828773 (Final)
    R828773C001 (2003)
    R828773C001 (2004)
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  • Journal Article Reible DD, Garcia M. Contaminant processes in sediment. American Society of Civil Engineers (ASCE) Sedimentation Manual. R828773C001 (2002)
    R828773C001 (2003)
    not available
    Journal Article Reible D, Mohanty S. A levy flight-random walk model for bioturbation. Environmental Toxicology and Chemistry 2002;21(4):875-881. R828773 (2004)
    R828773 (Final)
    R828773C001 (2002)
    R828773C001 (2003)
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  • Journal Article Thibodeaux LJ, Valsaraj KT, Reible DD. Bioturbation-driven transport of hydrophobic organic contaminants from bed sediment. Environmental Engineering Science 2001;18(4):215-223. R828773 (2004)
    R828773 (Final)
    R828773C001 (2002)
    R828773C001 (2003)
    R828773C001 (2004)
    R825513C011 (Final)
  • Abstract: Liebert-Abstract
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  • Journal Article Work PA, Moore PR, Reible DD. Bioturbation, advection, and diffusion of a conserved tracer in a laboratory flume. Water Resources Research 2002;38(6):24-1–24-9. R828773 (2004)
    R828773 (Final)
    R828773C001 (2003)
    R828773C001 (2004)
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  • Supplemental Keywords:

    bioturbation, bioavailability, biodegradation, biota-sediment accumulation factor, BSAF, sequestration, natural recovery, waste, water, analytical chemistry, bioremediation, contaminated sediments, environmental microbiology, hazardous, hazardous waste, microbiology, molecular biology, genetics, polycyclic aromatic hydrocarbon, PAH, biochemistry, bioremediation of soils, contaminants in soil, contaminated soil, contaminated soils, degradation, desorption-resistant contamination, microbial degradation, natural recovery, phytoremediation., RFA, Scientific Discipline, Waste, Water, Contaminated Sediments, Environmental Chemistry, Microbiology, Environmental Microbiology, Hazardous Waste, Bioremediation, Hazardous, degradation, microbial degradation, bioavailability, biodegradation, contaminated sediment, turbificid oligochaetes, PAH, contaminated soil, contaminants in soil, bioremediation of soils, desorption-resistant contamination, natural recovery, biochemistry, phytoremediation, bioturbation

    Relevant Websites:

    http://www.hsrc.org Exit
    http://www.sediments.org Exit

    Progress and Final Reports:

    Original Abstract
  • 2002 Progress Report
  • 2004 Progress Report
  • 2005
  • 2006
  • Final

  • Main Center Abstract and Reports:

    R828773    HSRC (2001) - South and Southwest HSRC

    Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
    R828773C001 Bioturbation and Bioavailability of Residual, Desorption-Resistant Contaminants
    R828773C002 In-Situ Containment and Treatment of Contaminated Sediments: Engineering Cap Integrity and Reactivity
    R828773C003 Phytoremediation in Wetlands and CDFs
    R828773C004 Contaminant Release During Removal and Resuspension
    R828773C005 HSRC Technology Transfer, Training, and Outreach